1. Field of the Disclosure
The present disclosure relates to a light emitting diode module, and more particularly, to a light emitting diode module with an improved structure providing an improved luminous efficiency for realizing white light or colored light while using a light emitting diode emitting blue or ultraviolet light and phosphor materials.
2. Description of the Related Art
A light emitting diode (LED) is formed of a light emitting source using compound semiconductors, such as GaAS, AlGaN, and AlGaAs, to generate various colors of light. LEDs can be easily manufactured and controlled compared to semiconductor lasers and have longer life spans than fluorescent lamps, and thus have replaced fluorescent lamps as the illumination light sources for next generation display devices. Recently, blue light emitting diodes and ultraviolet light emitting diodes which are produced using nitride materials and having excellent physical and chemical characteristics, have been introduced. In addition, as white light and other colors can be produced using blue or ultraviolet light emitting diodes together with phosphor materials, the application range of light emitting diodes has been enlarged.
LED modules using phosphor materials produce white light or other colors of light according to the principle that light emitted from the blue or ultraviolet light emitting diode and incident on the phosphor material transmits energy to the phosphor material, and thus light with a longer wavelength than incident light is emitted. For example, in a white light emitting diode module, photons of ultraviolet light emitted from the LED chip excite the phosphor material and thus a combination of red, green, and blue light or a combination of yellow and blue light is emitted from the excited phosphor material. The wavelengths of the visible light emitted from the phosphor material vary according to the composition of the phosphor material, and this combination of visible light appears as white light to human eyes.
FIG. 1 is a schematic view of a conventional LED module. Referring to FIG. 1, in the LED module, a light emitting chip 1 is disposed in a concave recess on a base 6, a first resin layer 3 is coated inside the base 6, and a second resin layer 4 and a third resin layer 5 are coated sequentially on top of the first resin layer 3.
However, in the configuration described above, the light extraction efficiency is low. Light extraction efficiency refers to the ratio of the amount of the light generated in the light emitting chips 1 to the amount of the light actually emitted from the LED module, and is directly related to the luminous efficiency, which denotes the illuminating performance of the LED module.
FIG. 2 illustrates the path of the light emitted by excited phosphor layers in the structure of the LED module of FIG. 1. Referring to FIG. 2, the light is emitted by the excited phosphor materials over 360°. Accordingly, light that is not fully emitted outward and is instead emitted in the downward direction of FIG. 2 is thus counted as loss resulting in a decrease in the luminous efficiency of the LED module.